Graphical models are omnipresent in the software engineering field, but most current graphical modeling languages do not scale with the increasing size and complexity of today’s systems. The navigation in the diagrams becomes a major problem especially if different aspects of the system are scattered over multiple, only loosely coupled diagrams. In this paper we present the hierarchical navigation capabilities of the Adora modeling tool. The user of this tool can freely control the level of detail in different parts of the model to reduce the size and complexity of the diagrams being displayed. Our fisheye visualization technique makes it possible to integrate all modeling aspects (structure, data, behavior, etc.) in one coherent model while keeping the size and complexity of the diagrams within reasonable limits.

Hierarchical diagrams are well-suited for visualizing the structure and decomposition of complex systems. However, the current tools poorly support modeling, visualization and navigation of hierarchical models. Especially the line routing algorithms are poorly suited for hierarchical models: for example, they produce lines that run across nodes or overlap with other lines. In this paper, we present a novel algorithm for line routing in hierarchical models. In particular, our algorithm produces an esthetically appealing layout, routes in real-time, and preserves the secondary notation of the diagrams as far as possible

When requirements models are developed in an iterative and evolutionary way, requirements validation becomes a major problem. In order to detect and fix problems early, the specification should be validated as early as possible, and should also be revalidated after each evolutionary step. In this paper, we show how the ideas of continuous integration and automatic regression testing in the field of coding can be adapted for simulation-based, automatic revalidation of requirements models after each incremental step. While the basic idea is fairly obvious, we are confronted with a major obstacle: requirements models under development are incomplete and semi-formal most of the time, while classic simulation approaches require complete, formal models. We present how we can simulate incomplete, semi-formal models by interactively recording missing behavior or functionality. However, regression simulations must run automatically and do not permit interactivity. We therefore have developed a technique where the simulation engine automatically resorts to the interactively recorded behavior in those cases where it does not get enough information from the model during a regression simulation run. Finally, we demonstrate how the information gained from model evolution and regression simulation can be exploited for locating defects in the model.

Editing graphic models always entails layout problems. Inserting and deleting items requires tedious manual work for shifting existing items and rearranging the diagram layout. Hence, techniques that automatically expand a diagram when space is required for insertion and contract it when free space becomes available are highly desirable. Existing layout generation algorithms are no good solution for that problem: they may completely rearrange a diagram after an editing operation, while users want to preserve the overall visual appearance of a diagram. We have developed a technique which automatically expands or contracts a diagram layout when items are inserted or removed while preserving its overall shape, i.e. the positions of the items relative to each other Our technique has been implemented in a prototype tool. We are using it not just for simplifying editing, but primarily for implementing an aspect-oriented visualization concept.